Impaired ability of patients with familial isolated vitamin E deficiency to incorporate alpha-tocopherol into lipoproteins secreted by the liver.
Plasma and lipoprotein alpha-tocopherol concentrations of four patients with familial isolated vitamin E deficiency and six control subjects were observed for 4 d after an oral dose (approximately 15 mg) of RRR-alpha-tocopheryl acetate labeled with six deuterium atoms (d6-tocopherol). Chylomicron d6-tocopherol concentrations were similar in the two groups. d6-Tocopherol concentrations of plasma, very low (VLDL), low (LDL), and high (HDL) density lipoproteins were similar in the two groups only during the first 12 h; then these were significantly lower, and the rate of disappearance faster, in the patients. The times (tmax) of the maximum chylomicron d6-tocopherol concentrations were similar for the two groups, but tmax values in the controls increased in the order: chylomicrons less than VLDL less than or equal to LDL approximately HDL, while the corresponding values in the patients were similar to the chylomicron tmax. Thus, plasma d6-tocopherol in controls increased during chylomicron and VLDL catabolism, whereas in patients it increased only during chylomicron catabolism, thereby resulting in a premature and faster decline in the plasma tocopherol concentration due to a lack of d6-tocopherol secretion from the liver. We suggest that these patients are lacking or have a defective liver "tocopherol binding protein" that incorporates alpha-tocopherol into nascent VLDL.
Traber
M G
MG
Department of Medicine, New York University School of Medicine, New York 10016.
Sokol
R J
RJ
Burton
G W
GW
Ingold
K U
KU
Papas
A M
AM
Huffaker
J E
JE
Kayden
H J
HJ
D000042:Absorption; D000328:Adult; D002914:Chylomicrons / Q000096:biosynthesis; D005260:Female; D006801:Humans; D008074:Lipoproteins / Q000096:biosynthesis*; D008099:Liver / Q000378:metabolism*; D008297:Male; D014810:Vitamin E / Q000378:metabolism*; D014811:Vitamin E Deficiency / Q000378:metabolism*
D002914:Chylomicrons; D008074:Lipoproteins; D014810:Vitamin E